Koster has sued the state of California over a law requiring producers who sell eggs in that state to provide hens with enough room in their cages to stand up, turn around and spread their wings. Complying with that standard would create economic burdens for Missouri egg producers, he says.

California's standard is reasonable. Few consumers want to think about this when they're enjoying an omelet, but most egg-producing hens in the United States are stacked in cages so cramped their muscles and bones waste away. They suffer unduly so that egg producers, which are mostly large agricultural corporations, can enjoy healthy profits.

Fortunately — in part because of the California law — the industry is starting to move toward more humane treatment of egg-laying hens. It's significant that egg producers themselves have not taken legal action against California's new standard. Neither have attorneys general from the largest egg-producing states — or any other state.

Just Missouri.

Koster argues that the U.S. Constitution's Commerce Clause prevents one state from regulating the agricultural practices of other states. He says his lawsuit should cost Missouri taxpayers no more than $10,000.

That sounds low for a federal case. And perhaps not an easy one. Producers and sellers of foie gras made the same argument after California banned force-feeding of ducks and geese in order to produce an oversized liver. The U.S. Court of Appeals for the Ninth Circuit rejected the claim, saying California was not restricting any state's commerce because its law treated in-state and out-of-state producers the same.

Koster announced his intention to file the lawsuit at a meeting of the politically influential Missouri Farm Bureau, which balks at nearly any attempt to legislate agricultural practices. He has rolled out a lame slippery slope argument — what if California required that soybeans be harvested by hand, for instance?

We haven't heard much of a call for hand-picked soybeans. But plenty of people want their eggs to be produced in humane and safe conditions.